Function of ompR gene in Pseudomonas chlororaphis HT66

Abstract:

[Background] Plant rhizosphere growth-promoting bacteria are one of the hotspots in the current research of agricultural microorganisms because they promote plant growth or have antagonistic effects on pathogenic bacteria. Among them, Pseudomonas chlororaphis HT66 is a non-pathogenic biocontrol strain that can efficiently synthesize phenazine-1-carboxamide (PCN) — a promising and environmental friendly agricultural antibiotic. [Objective] To study the physiological function of ompR gene in P. chlororaphis HT66 and its biocontrol efficiency. [Methods] The ompR gene deletion mutant of HT66 strain was constructed by scar-less gene knockout method. We studied the effects of the mutation on the growth rate, biofilm synthesis, tolerance to pH and osmotic pressure, swarming mobility and PCN production. [Results] Compared with the wild-type strain, the ompR gene deletion inactivated mutant showed a slight reduction in cell biomass. The biofilm decreased by 31.5%, whereas the swarming mobility of the strain and the tolerance to osmotic pressure and pH decreased. However, the yield of PCN increased by 57.8% in the mutant strain. In HT66 strain, the ompR gene has a certain degree of regulation of its motility, environmental tolerance and physiological and biological functions. [Conclusion] Our findings enriched the metabolic pathway of P. chlororaphis, and will provide a basis for the research and application of the subsequent PCN synthesis mechanism.

Key words:Pseudomonas, gene knockout, ompR, phenazine-1-carboxamide